Swing type rotary compressors having a cut-off portion on the roller

ABSTRACT

In a swing type rotary compressor, a roller (2) is fitted on an eccentric portion (31) of a drive shaft (3) and installed within a cylinder chamber (11) so as to be able to orbit. On the roller (2), a blade (21) partitioning the cylinder chamber (11) into a compression chamber (X) and a suction chamber (Y) to which a suction port (13) is opened is integrally protruded. On the cylinder (1), a support body (4) swingably supporting the blade (21) is swingably supported. On an outer circumferential surface of the roller (2), a cutoff portion (22) extending forward in a rotation direction from near a blade protruding position on the roller (2) and shifting a suction shut-off point for suction gas sucked from the suction port (13) toward a side of the compression chamber (X) is formed on a side of the suction chamber (Y) with respect to the blade protruding position. With the configuration, only by forming the cut-off portion with a simple cutting operation applied on an outer circumference of the roller (2), suction resistance in sucking suction gas into the suction chamber (Y) and passage resistance in supplying suction gas from the compression chamber (X) to the suction chamber (Y) via the cut-off portion (22) are reduced and thus, its compression capacity can be exactly adjusted. Furthermore, its manufacturing cost can be reduced by sharing various parts in common.

TECHNICAL FIELD

The present invention relates to a swing type rotary compressorprimarily employed in a refrigeration apparatus.

BACKGROUND ART

Generally, rotary compressors are set to different predeterminedcompression capacities depending on models, and in order to reduce theircost as low as possible, capacities thereof are adjusted by changing aneccentricity amount of a drive shaft and an outer diameter of a rollerwithout changing a shape of a cylinder of the compressor. In this case,however, while the cylinder can be made common between different models,the control of parts becomes complicated because the kinds of driveshafts and rollers increase in number. In addition, there has been sucha problem that changes in their production line and changes in centeringbecome necessary, resulting in cost increase.

Furthermore, while there is known an inverter controlled type rotarycompressor which is made variable in its compression capacity by controlof the number of revolutions to achieve the use of the same of parts,because such an inverter-controlled compressor is very expensive, arefrigeration apparatus incorporating such a compressor becomes veryexpensive in manufacturing cost.

As a result, as another means for adjusting the compression capacity ofthe rotary compressor, there is conventionally known, as described inJapanese Utility Model Application Laid-Open Publication No. 54-29403, amethod constituted so that a thin plate is inserted between a cylinderand a front head or a rear head, a bypass passage communicating, atstarting time of suction, a suction chamber in which a suction port ofthe cylinder opens with a compression chamber in which a discharge portopens is formed on said thin plate and the compression capacity isadjusted by shifting a suction shut-off position of suction gas towardthe compression chamber side.

Namely, said capacity adjustment method is constructed as follows. Asshown in FIG. 6, in a rotary compressor wherein, in a cylinder chamberA1 of a cylinder A arranged between a front head and a rear head, aroller B is internally installed with an eccentric portion C1 of a driveshaft C being fitted on said roller B, and on an intermediate positionbetween a discharge port A2 and a suction port A3 formed on saidcylinder A. A blade D divides an inner space of said cylinder chamber A1into a compression chamber X communicating with said discharge port A2and a suction chamber Y communicating with said suction port A3 and theblade D reciprocably mounted. A rear end of said blade D is urged by aspring D1 so as to contact a tip end thereof with an outer circumferenceof said roller B at all times. A circular thin plate E having the samediameter as that of said cylinder A and having a shaft hole E2 piercedby said drive shaft C at the center thereof is inserted between saidfront head and said cylinder A. A bypass passage E1 shifting the suctionshut-off position of suction gas sucked from said suction port A3 intosaid suction chamber Y toward said compression chamber X side is formedon this thin plate E. Said bypass passage E1 is formed in a longcircular arc shape along an inner wall of said cylinder chamber A1 andsaid bypass passage E1 is formed through the thickness of said thinplate E.

Accordingly, with said configuration, the internal space of saidcylinder chamber A1 is partitioned, by the blade D and a contact point Oin which the outer circumference of said roller B is brought intocontact with the inner wall face of said cylinder chamber A1, into asuction chamber Y formed between the contact point O and a wall face ofthe blade D in the forward side of the rotation direction of saideccentric shaft portion C1 and a compression chamber X formed betweensaid contact point O and a wall face of the blade D in the backward sideof the rotation direction of said eccentric shaft portion C1. Whendriving the drive shaft C, said contact point O of the roller B with theinner wall of said cylinder chamber A1 is moved along the inner wall ofsaid cylinder chamber A1 and gas is sucked into said suction chamber Yfrom said suction port A3 and compressed in said compression chamber Xto be discharged from said discharge port A2, and thus, the suction andcompression of gas is repeated. In addition, because said thin plate Eis inserted between said cylinder A and front head, when said contactpoint O is positioned at the bypass passage E1 formed on said thin plateE, said compression chamber X and said suction chamber Y arecommunicated with each other and the gas within said compression chamberX is not compressed. First when said contact point 0 has passed thebypass passage El, suction of suction gas is shut off and the suctionchamber Y and compression chamber X are partitioned in a hermeticallysealed state, and thus the compression of gas in the compression chamberX is started. Therefore, by shifting the shut-off position of suctiongas to the compression chamber by an arbitrary amount toward thecompression chamber X side through changing the length of said bypasspassage El, the start time-point of gas compression in the compressionchamber X is adjusted and thus, the compression volume in thecompression chamber X can be adjusted. In other words, the compressioncapacity in said compression chamber X becomes controllable arbitrarilyand the variation in the capacity of said rotary compressor is enlarged.

However, in said configuration, because a thin plate provided with saidbypass passage E1 is required separately, the number of parts isincreased and assembly man-hours thereof are increased that much,resulting in complication of the over-all construction. In addition,because said bypass passage E1 has only the passage area correspondingto the thickness of said thin plate E inserted between said cylinder Aand front head, not only it is necessary to guide suction gas suckedinto the suction chamber Y from said suction port A3 to an axialdirection end side of said cylinder A where said thin plate E isarranged but also the resistance when the suction gas within saidsuction chamber Y passes through said bypass passage E1 is increased,resulting in the problem that an exact control of the compressioncapacity becomes difficult.

DISCLOSURE OF THE INVENTION

The present invention has been developed by focusing the fact that, in aswing type rotary compressor wherein a blade partitioning a cylinderchamber of a cylinder into a compression chamber and a suction chamberis formed integrally with a roller arranged in said cylinder chamber,said roller is revolution-driven without rotating in said cylinderchamber and a circumferential position of said roller facing its suctionport is not greatly shifted relative to said suction port. The object ofthe present invention is to provide a swing type rotary compressor whichis able to exactly adjust its compression capacity, while reducing theresistance in by-passing suction gas only by applying a simple cuttingoperation, etc. on an outer circumference of said roller and to reducethe manufacturing cost through commonness of various parts withoutraising the complication of parts control.

In order to achieve the above-described object, a swing type rotarycompressor of the present invention is characterized by comprising acylinder having a cylinder chamber inside said cylinder;

a roller fitted on an eccentric portion of a drive shaft and installedin said cylinder chamber so as to be able to revolve;

a blade integrally formed on said roller so as to protrude therefrom andpartitioning said cylinder chamber into a compression chamber and asuction chamber to which a suction port is opened;

a support body swingably supported on said cylinder and swingablysupporting said blade; and

a cut-off portion formed on an outer circumference of said roller of aside of the suction chamber with respect to a protruding position fromwhich the blade protrudes and extending from the vicinity of theprotruding position forward in a revolution direction so as to shift asuction shut-off position for suction gas sucked from said suction porttoward a side of the compression chamber.

In the swing type rotary compressor constructed as described above,because the cut-off portion extending in the revolution direction fromnear the protruding position of the roller and shifting the suctionshut-off position on the suction chamber toward the compression chamberside is formed on the outer circumference of the roller, while thecut-off portion of the roller is adjacently confronted with the innerwall face of the cylinder chamber, the compression chamber and thesuction chamber are communicated with each other through the cut-offportion. Therefore, gas compression within the compression chamber isnot started even when the roller is revolution-driven by the drive ofthe drive shaft. First when the outer circumferential surface ahead ofthe cut-off portion in the revolution direction contacts the inner wallface of the cylinder chamber, the compression chamber is hermeticallypartitioned from the suction chamber and the gas compression is startedwithin the compression chamber.

Because the roller integrally protruding the blade is revolution-drivenin the cylinder chamber, only by forming on the outer circumference ofthe roller the cut-off portion arbitrarily in a circumferential length,the suction shut-off position of suction gas on the compression chamberis arbitrarily shifted toward the compression chamber side, that is, tothe forward side in the revolution direction of the roller from theopening of the suction port and thus, the compression volume in thecompression chamber can be adjusted by adjusting the starting time ofgas compression in the compression chamber, and the variation in thecapacity of the swing type rotary compressor can be enlarged.

In addition, only by forming the cut-off portion in an arbitrary depth,the suction resistance at suction of suction gas can be reduced with aspace formed by the cut-off portion, and a simple and exact adjustmentof compression capacity of the rotary compressor can be made whilereducing a passage resistance in passing through the cut-off portion.Furthermore, in effecting the adjustment of the compression capacity,parts other than the roller can be used as common parts, andconsequently, the manufacturing cost can be reduced through thecommonness of various parts without raising the complication of partscontrol.

In an embodiment of the present invention, a concave portion for guidingthe suction gas introduced from the suction port to the suction chamberside is formed at a position of the cut-off portion confronting thesuction port. In this case, the space near the opening of the suctionport at the start of suction can be enlarged by the concave portion andthe suction gas from the suction port can be smoothly guided to theforward side of the suction chamber in the revolution direction.Accordingly, with the suction gas being introduced with that much lesssuction resistance and more smoothness, the suction chamber iscommunicated to the compression chamber through the cut-off portion, andthus, the compression capacity of the compressor can be adjustedcorrectly.

When the cut-off portion is provided on the roller over the entire axiallength thereof and both axial ends thereof are opened to the axial endfaces of the roller, the cut-off portion can be simply formed with anend mill and so on. Furthermore, even when the suction port is formed inany axial position of the cylinder or on the front head or rear head,the suction port can be opened to the cut-off portion. As a result, thesuction resistance from the suction port to the suction chamber can bereduced and with passage resistance from the suction chamber to thecompression chamber being held low, the compression capacity can beexactly adjusted.

Furthermore, the cut-off portion can be formed on an intermediateportion in the axial length of the roller so as to be closed to theaxial end portions of the roller. Particularly in the case of formingthe suction port in the cylinder, because the suction port is generallyformed in an axially intermediate portion of the cylinder, the cut-offportion is confronted with the opening of the suction port and thus, thesuction gas resistance to the cut-off portion can be reduced, and byforming the cut-off portion closed to both axial ends of the roller, apredetermined thickness can be obtained at both axial end faces of theroller. Therefore, as compared with the case of forming the cut-offportion over the entire axial length of the roller so as to be opened toaxial both end faces of the roller, a predetermined thickness can besecured on axial end faces of the roller and thus, leakage of highpressure oil and refrigerant through the clearances between axial bothend faces of the roller and the respective heads can be suppressed.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a plan view showing an essential portion of a swing typerotary compressor according to a first embodiment of the presentinvention;

FIG. 2 is a perspective view showing a roller of the first embodiment;

FIG. 3 is a perspective view showing a roller in a second embodiment;

FIG. 4 is a perspective view showing a roller in a third embodiment;

FIG. 5 is a plan view showing the state where a roller is installed in acylinder chamber in a fourth embodiment of the present invention;

FIG. 6 is a plan view showing a conventional example example; and

FIG. 7 is a sectional view through the middle of a roller showing a viewsimilar to FIG. 5 with a concave portion in an axially intermediatecut-off portion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 shows an essential part of a swing type rotary compressoraccording to the present invention. In the rotary compressor, a roller 2is provided in a cylinder chamber 11 of a cylinder 1 inserted between afront head and a rear head. An eccentric portion 31 of a drive shaft 3is fitted in the roller 2, so that the roller 2 is revolved in adirection indicated by an arrow while an outer circumference of theroller is in contact with the inner wall face of the cylinder chamber 11according to the rotation of the drive shaft 3. Furthermore, the outercircumference of the roller 2 is integrally provided with a blade 21protruding outward in an radial direction therefrom. A support body 4 isrotatably provided at an intermediate position between a discharge port12 and a suction port 13 provided on the cylinder 1 so that the blade 21is supported on the support body 4 so as to be swingable and movableback and forth.

By partitioning the cylinder chamber 11 into a suction chamber Ycommunicating with the suction port 13 and a compression chamber Xcommunicating with the discharge port 12 with the blade 21 protrudedfrom the roller 2 and by moving the outer circumference of the roller 2along the inner wall face of the cylinder chamber 11 in contacttherewith according to the rotation of the drive shaft 3, gas is suckedinto the suction chamber Y from the suction port 13 and compressed inthe compression chamber X so as to be discharged from the discharge port12, and thus, gas suction and compression is repeated.

In the above-described configuration, firstly a first embodiment of thepresent invention is described below with reference to FIGS. 1 and 2. Inthe first embodiment, a cut-off portion 22 extending from near a baseportion of the roller 2 from which the blade 21 protrudes forward in arevolution direction of the roller and shifting a suction shut-offposition for suction gas sucked to the side of the suction chamber Yfrom the suction port 13 toward the compression chamber X side, that is,the forward side in the revolution direction of the roller 2 is formedon the suction chamber Y side of the outer circumference of the roller2.

In other words, the cut-off portion 22 is formed, as shown in FIGS. 1and 2, so as to extend by a predetermined length in the circumferentialdirection from a position on the circumference confronting the suctionport 13 toward the forward side in the revolution direction of theroller 2. Further, the cut-off portion is formed over an entire axiallength of the roller and both ends of the cut-off portion 22 in theaxial direction are opened to both axial end faces of the roller 2.

With the above-described configuration, when a contact point of theouter circumference of the roller 2 (in the cut-off portion 22, a chainline in FIG. 1) with the inner wall of the cylinder chamber 11 isdesignated with O, in the case where the contact point O is positioned,as shown in FIG. 1,in the range of the cut-off portion 22, the suctionchamber Y and the compression chamber X are communicated to each othervia the cut-off portion 22. As a result, the gas in the compressionchamber X flows to the suction chamber Y, and the gas compression in thecompression chamber X is not started. First, when the contact point O isshifted forward in the revolution direction of the roller 2 so as tobring the outer circumferential face of the roller on the forward sideof the cut-off portion in the revolution direction into contact with theinner wall of the cylinder chamber 11, the compression chamber X becomesclosed hermetically to the suction chamber Y and the gas compressionwithin the compression chamber X is started.

Because the present embodiment is a swing type rotary compressoremploying the roller 2 with a protruding blade 21 integrally providedthereon, the roller 2 is orbited within the cylinder chamber 11 andthus, only by forming the cut-off portion 22 on the roller 2 with itscircumferential length being set at will, the suction shut-off point ofthe compression chamber X for the suction gas in the suction chamber Ycan be shifted at will toward the compression chamber X side, that is,forward in the revolution direction of the roller 2 with respect to theopening of the suction port 13. Therefore, the start timing of gascompression within the compression chamber X can be adjusted so as toadjust the compression volume of the compression chamber X. Namely, thecompression capacity in the compression chamber X becomes adjustable atwill and the variation in the capacity of the swing type rotarycompressor can be enlarged.

Furthermore, because the cut-off portion 22 can be formed in anarbitrary depth on the outer circumference of the roller 22, byconfronting the cut-off portion 22 with the suction port 13 and forminga space on the cut-off portion 22, the suction resistance at suction ofsuction gas can be reduced and the passage resistance can be reducedwhen suction gas passes through the cut-off portion 22, while theadjustments of compression capacity can be made exactly and simply. Inaddition, because parts such as the cylinder 1 and drive shaft 3 otherthan the roller 2 formed with the cut-off portion 22 can be used ascommon parts, the manufacturing cost can be reduced through thecommonness of parts without raising the complication of partsmanagement.

Furthermore, when the cut-off portion 22 is formed, as shown in FIGS. 1and 2, over the entire axial length of the roller 2 with both axial endsthereof being opened to the both axial end faces of the roller 2, thecut-off portion can be simply formed such as by an end mill.Furthermore, even when the suction port 13 is formed in any axialposition of the cylinder 1 or on the front head or rear head, thesuction port 13 can be opened toward the cut-off portion 22. As aresult, the suction resistance from the suction port 13 to the suctionchamber Y can be reduced and the passage resistance from the suctionchamber Y to the compression chamber X can be reduced, while thecompression capacity can be exactly adjusted.

Furthermore, as in a second embodiment shown in FIG. 3, cut-off portions22 may be formed respectively only on axially end portions of the roller2. Such configuration is particularly effective for the case where asuction port 13 is provided respectively on the front and rear headarranged on both side of the cylinder 1, and the suction gas introducedis from the suction port 13 can be guided with less suction resistanceand the compression capacity control can be made exactly.

In addition, as in a third embodiment shown in FIG. 4, a cut-off portion22 may be formed on an axially intermediate portion of a roller 2 so asto be closed to both axial end faces thereof. With such configuration,particularly when the suction port 13 is provided on the cylinder 1,because the suction port 13 is generally formed on an axiallyintermediate portion of the cylinder 1, the adjustment of thecompression capacity can be made exactly while the suction gasresistance to the cut-off portion is held low. Furthermore, when thecut-off portion 22 is formed on the axially intermediate portion of theroller 2 so as to be closed to both axial end faces thereof, because apredetermined thickness can be secured at axial both end faces of theroller 2, the leakage through clearances between axial both end faces ofthe roller 2 and respective heads can be reduced. Namely, the inner sideof the roller 2 is brought into a high pressure state filled with highpressure lubrication oil, etc., while the outer circumferential side ofthe roller 2 confronting the suction chamber Y is in a low pressurestate filled with suction gas. Accordingly, the pressure differencebetween the inner side and outer side of the roller 2 near the suctionport 13 becomes large. Meanwhile, both axial end faces of the roller 2are in face-to-face contact with the front head and rear head.Therefore, according to the third embodiment, because a predeterminedthickness can be secured on the axial both ends of the roller 2, theleakage through clearances between both axial end faces of the roller 2and the respective heads due to the pressure difference can be reduced,as compared with the case where the cut-off portion 22 is formed overthe entire axial length so as to be opened to both axial end faces ofthe roller 2 as in the first embodiment.

Furthermore as shown in a fourth embodiment in FIG. 5, a concave portion22a may be provided on a position of a cut-off portion 22 confronting asuction port 13 for guiding suction gas introduced from the suction port13 to the side of the suction chamber Y. By doing so, the suctionresistance at the start of suction from the suction port 13 can befurther reduced. Further, the suction gas from the suction port 13 canbe introduced with less suction resistance and more smoothly toward theforward side in the revolution direction of the suction chamber Y, andcan be smoothly bypassed from the suction chamber Y to the compressionchamber X via the cut-off portion 22, and thus, the adjustment of thecompression capacity can be made exactly. In the embodiment having theconcave portion 22a of FIG. 5, the cut-off portion 22 can extendcompletely across the roller 2 as shown in FIGS. 1 and 2 or can be atleast one of the cut-off portions 22 at the axial ends of roller 2 asshown in FIG. 3. Also, the concave portion 22a, can be provided in theaxially intermediate cut-off portion 22 as shown in the embodiment ofFIG. 4 and as indicated in the sectional view of FIG. 7.

The swing type rotary compressor according to the present invention isprimarily employed in the refrigeration apparatus. The invention beingthus described, it will be obvious that the same may be varied in manyways. Such variations are not to be regarded as a departure from thespirit and scope of the invention, and all such modifications as wouldbe obvious to one skilled in the art are intended to be included withinthe scope of the following claims.

What is claimed is:
 1. A swing type rotary compressor which comprisesacylinder having a cylinder chamber inside said cylinder; a rotatableroller fitted on an eccentric portion of a drive shaft and installed insaid cylinder chamber, the roller being rotatable in a revolutiondirection; a blade integrally formed on said roller and protrudingtherefrom to partition said cylinder chamber into a compression chamberand a suction chamber, a suction port being open to the suction chamberover a length in a circumferential direction; a support body swingablysupported on said cylinder and swingably supporting said blade; and acut-off portion formed on an outer circumference of said roller on aside of the suction chamber with respect to a protruding position fromwhich the blade protrudes and extending from the vicinity of theprotruding position forward in the revolution direction over a length ina circumferential direction greater than the length of the suction portin the circumferential direction so as to shift a suction shut-offposition for suction gas sucked from said suction port toward a side ofthe compression chamber.
 2. The swing type rotary compressor asdescribed in claim 1, wherein said cut-off portion is formed over anentire axial length of the roller and both axial ends of said cut-offportion are opened to both axial end faces of the roller.
 3. The swingtype rotary compressor as described in claim 1, wherein said cut-offportion is formed on an axially intermediate portion of the roller so asto be closed to both axial end faces of the roller.
 4. The swing typerotary compressor as described in claim 1, wherein the cut-off portionhas a length in a circumferential direction which is more than adiameter of the suction port so as to shift the suction shut-offposition toward the compression chamber by a length more than thediameter of the suction port.
 5. The swing type rotary compressor asdescribed in claim 1, wherein the suction chamber and the compressionchamber are in communication through the cut-off portion during aportion of the rotation of the roller.
 6. The swing type rotarycompressor as described in claim 1, wherein the cut-off portion extendsalong a circumference of the roller in the revolution direction.
 7. Theswing type rotary compressor as described in claim 1, wherein a concaveportion is provided on said cut-off portion at a position confrontingthe suction port, the concave portion guides suction gas introduced fromthe suction port toward the side of the suction chamber.
 8. The swingtype rotary compressor as described in claim 7, wherein said cut-offportion is formed over an entire axial length of the roller and bothaxial ends of said cut-off portion are opened to both axial end faces ofthe roller.
 9. The swing type rotary compressor as described in claim 7,wherein said cut-off portion is formed on an axially intermediateportion of the roller so as to be closed to both axial end faces of theroller.
 10. The swing type rotary compressor as described in claim 7,wherein the cut-off portion extends in the revolution direction of theroller.
 11. The swing type rotary compressor as described in claim 10,wherein the cut-off portion has an upstream side and a downstream siderelative to the revolution direction and wherein the concave portion islocated at the upstream side of the cut-off portion.
 12. The swing typerotary compressor as described in claim 7, wherein the cut-off portionhas a first depth and the concave portion has a second maximum depth inthe roller and wherein the second maximum depth of the concave portionis greater than the first depth of the cut-off portion.